This introduces the new type -- Semantics.
Semantics maps SyntaxNodes to various semantic info, such as type,
name resolution or macro expansions.
To do so, Semantics maintains a HashMap which maps every node it saw
to the file from which the node originated. This is enough to get all
the necessary hir bits just from syntax.
3228: Use proper range for hover on macro arguments r=matklad a=edwin0cheng
This PR use `original_range` to remap the range of found syntax node in `hover` and thus it should return the proper text range now.
fixed#3000fixed#3135
Co-authored-by: Edwin Cheng <edwin0cheng@gmail.com>
